;(function(){
    rem()
    window.onresize = () => rem()
    function rem () {
        let htmlWidth = document.documentElement.clientWidth || document.body.clientWidth;
        if (htmlWidth>750) htmlWidth=750
        let htmlDom = document.getElementsByTagName('html')[0];
        htmlDom.style.fontSize= htmlWidth/375*100 + 'px';
    }
})();

